Along with widespread of mobile communication techniques, wireless communication techniques used in mobile devices are generally required to connect a base station (BS) or a wireless access point (AP) to implement communication between the mobile devices, i.e. the BS or wireless AP has to be used to implement communication between the mobile devices, for example, a general packet radio service (GPRS) technique, a code division multiple access (CDMA) technique, a WIFI (IEEE 802.11) communication technique, etc. When the mobile device is located at a place with a poor signal reception or a place with none BS or wireless AP around, the mobile device could not communicate with other mobile devices. For example, when most of the BSs could not be used due to natural disasters, the user's mobile device could not communicate with others. Therefore, a technique of implementing device-to-device communication without using the BS or the wireless AP is required to be developed, i.e. the so-called device-to-device (D2D) direct communication.
The D2D direct communication refers to that various electronic devices directly perform data transmission, control, data sharing, or make phone call, etc. with each other through a corresponding communication protocol (for example, a Bluetooth protocol, a WIFI direct protocol, etc.) without using the BS or the wireless AP to perform intermediary management. The direct communication could also be referred to as D2D communication, proximity-based system, direct communication, smart direct link, etc. Presently, a new generation standard wireless communication technique researched and developed in a third generation partnership project (3GPP), for example, a long term evolution (LTE) technique, and a LTE advanced technique, etc., also hopes to integrate the direct communication technique into the LTE technique.